Notes on some new or little known Rot$era from Brazil

Hendrik SEGERS, S. S. S. SAR&~A (1)

ABSTRACT

The rotifer fauna of fhree localities near Boa Vista (Roraima, Brazil) is studied. A total of 66 species is identified, 6’ of which are new to Brazil. Macrochaetus aspinus sp. n., M. americanus sp. n. and Trichocerca abilioi sp. n. are described. Lepadella latusinus Stri&a Koste, Dicranophorus halbac.hi Kosie and Trichocerca parvula Carlin are recognized as synonyms of L. c.ostatoides Segers, D. kostei Pourriot and Zoppi de Roa and T. rotundata Myers, respectively.

KEYWORDS : Rotifera - Brazil - New species - Taxonomy - Zoogeography.

NOTES SUR QUELQUES ROTIFÈRES NOUVEAUX ou PEU CONNUS DU BRÉSIL

La présente contribufion concerne la faune de rotifères de trois localités dans les environs de Boa Vista (Roraima, Brésil). Au fatal, 66 espèces ont été identifiées, dont 6 nouvelles pour la faune brésilienne. Macrochaetus aspinus sp. n., M. americanus sp. II. et Trichocerca abilioi sp. n. sonl décrites. Lepadella latusinus striata Koste, Dicranophorus halbachi Koste et Trichocerca parvula Carlin sont reco-nnues comme synonymes de L. costatoides Segers, D. kost.ei Pourriot et Zoppi de Roa et T. r0tundat.a Myers, respectivement.

MOTS CLÉS : Rotifères - Brésil - Espèces nouvelles - Taxonomie - Zoogéographie.

RESUMEN

NOTAS SOBRE ALGUNOS ROTiFEROS NUEVOS 0 POCO CONOCIDOS DE BRASIL

El estudio de 10s rotiferos de fres localidades de la region de Boa Vista (Roraima, Brasil) ha resultado en la idenfificaci& de 66 especies, de las cuales 6 son nuevas para Brasil. Tres nuevas especies han sido descritas : MacrochaetSus aspinus sp. n., M. americanus sp. II. y Trichocerca abilioi sp. n. Lepadella latusinus striata Koste, Dicranophorus halbachi Koste y Trichocerca parvula Carlin han sido reconocidas coma siminimos de L. costa- toides Segers, D. kostei Pourriot y Zoppi de Roa y T. rotundata Myers, respectivamente.

PALABRAS ~LAVES : Rotifera - Brasil - Nuevas especies - Taxonomia - Zoogeografia.

(1) Institufe of Animal Ecology, K. L. Ledeganckstraat 35, B - 9000 Gent, Belgium.

R~U. Hydrobiol. irop. 26 (3) : 175-185 (1993).

176 H. SEGERS, S. S. S. SARMA

INTRODUCTION

Neotropic Rotifera have been relatively well- st.udied, when compared to many other tropical regions. Major contributions date as far back as 1913, when MURRAY published several papers on the bdelloid (MURRAY, 1913 a) and monogonont (MURRAY, 1913 b, c) rotifers of South America. Later, HAUER (1956, 1964, 1965 a, 1965 b) and, especially, KOSTE (1972, 1974, 1986, 1988, 1989), BRANDORFF et al. (1982), KOSTE and ROBERTSON (1983), KOSTE et al. (1984), KOSTE and HARDY (1984), KOSTE and BOTTGER (1989) added signiflcantly to the knowledge of Brazilian Rotifera.

The relatively high number of endemic species and the highly diverse rotifer taxocoenosis of its fresh- wat,er habit.ats offer an explanation for the lasting attract.ivity of the region as subject for studies on Rotifera. This is reflected in the large number of recent contributions becoming available (e.g., BAT- TISTONI, 1992; KOSTE and B~TTGER, 1992; KOSTE and ROBERTSON, 1990; KUCZYNSKI, 1991 a,1991 b; NEUMANN-LEITAO, 1990; SAMANEZ, 1991; SEGERS ef al., 1993 b; TURNER, 1990 a, 1990 b; TURNER and D4 SILVA, 1992). Nevertheless, still a lot remains to be discovered on the taxonomy, distribution and ecology of these organisms, as illustrated here.

VENEZUELA

MATERIAL AND METHODS

Samples were collected by dragging a 50 prn plankton net through the littoral vegetati&i of seve- ral water bodies in the region of Boa Vista, Roraima, Brazil (map 1). Of these, we were able to examine samples from three localities as listed below.

- Locality 1. Temporary lagoon, + 50 m long, 40 m wide, depth up to 1 m, about 5 km S. of Boa Vista, Roraima, Brasil, 24 June 1987. Conductivity 5.7 PS ; 02 7.2 mg/1 ; TO (surface) 32.9 OC ; pH 6.1.

- Locality 2. Permanent lagoon .along Rio Branco, about 7 km S. of Boa Vista, Roraima, Bra- sil, 24 June 1987. Conductivity 5.7 +S ; Os 7.1 mg/1 ; TO (surface) 36.6 OC; pH 5.3.

- Locality 6. Temporary inundation pond, of side st.ream of Rio Branca, near Mucajai, Roraima, Brasil, 24 June 1987. Conductivity 10.5 PS; 02 6.1 mg/1 ; TO (surface) 36.4 OC ; pH 4.0.

Al1 samples are qualitative, and preserved in for- malin. Selection and study of rotifer specimens was done using a Ml0 dissecting microscope and a Medi- lux 12 (Kyowa) microscope. Drawings were made using a camera lucida.

Type specimens are deposited in the Instituto National de Pesquisas da Amazônia, Manaus,

MAP 1. - Roraima State, Brazil, indicating the sampling stations. État de Roraima, Brésil, aoec localisation des stations de récolte.

Rat. Hydrobiol. trop. 26 (3) : 175-185 (1993).

NEW OR LITTLE KNOWN ROTIFERA (BRAZIL) 177

Brazil (I.N.P.A.), the Koninklijk Belgisch Instituut voor Nat.uurwetenschappen, Brussels, Belgium (K.B.I.N.), and the Institute of Animal Ecology, University of Gent,, Belgium (R.U.G.)

Al1 measurements are in p,rn.

RESULTS AND DISCUSSION

A list of the monogonont, Rotifera identified from the samples examined is provided below, where numbers refer to the sampling station, * for species new to Brazil and ** indicates a species new to the neotropics region.

Asplanchna sieboldi (Leydig) : 1 Cephalodella mira Myers : 1 C. mucronata Myers : 6 Colurella uncinata (0. F. Müller) f. bicuspidata

(Ehrenberg) : 1 Dicranophorus epicharis Harring and Myers : 2 D. kostei Pourriot and Zoppi de Roa : 1 ** D. prionacis Harring and Myers : 1, 2 D. sebastus Harring and Myers : 6 Euchlanis incisa Carlin : 2 Lecane arcula Harring : 2 L. braziliensis Segers-; 2 L. bulla (Gosse) : 2, 6 L. cornufa (0. F. Müller) : 1 L. crepida Harring : 1, 2 L. curuicornis (Murray) : 1, 2, 6 L. decipiens (Murray) : 6 L. dumonti Segers : 1, 6 L. eutarsa Harring and Myers : 1, 2 L. L.

furcata (Murray) : 1, 2 haliclysta Harrmg and Myers :.6

L. hamata (Stokes) : 1, 2, 6 L. hornemanni (Ehrenberg) : 1, 2, 6 L. inopinata Harring and Myers : 6 L. leontina (Turner) : 1, 6 L. ludwigii (Eckstein) : 1, 2, 6 L. Zunaris (Ehrenberg) : 1, 2, 6 L. monosfyla (Daday) : 2 L. nelsoni Segers : 1, 2, 6 L. obtusa (Murray) : 2, 6 L. pertica Harring and Myers : 1, 6 L. pyriformis (Daday) : 1 L. rhenana Hauer : 2 L. ruttneri Hauer : 6 L. signifera (Jennings) : 1, 2, 6 * L. sola Hauer : 2 Lepàdella acuminafa (Ehrenberg) : 6 L. amphitropis Harring : 1, 2 L. costatoides Segers : 2. L. cryphaea Harring : 2 ** L. quadricarinata (Stenroos) : 2 L. quinquecostata (Lucks) (incl. f. chrisfineae Koste) : 1

** Lindia fuloa Harring and Myers : 2 Macrochaetus alfamirai (Arevalo) : 2 M. americanus n. sp. : 2 M. aspinus n. sp. : 2 M. collinsi (Gosse) : 1, 2 fil. sericus (Thorpe) : 2 Monommata maculata Harring and Myers : 1, 6 Mytilina oentralis (Ehrenberg) (diverse formae) : 1 Notommata copeus Ehrenberg : 1, 2 N. pachyura (Gosse) : 1 Plationus pafulus (0. F. Miiller) : 2 Polyarthra oulgaris Carlin : 1, 6 Taphrocampa annulosa Gosse : 2 Testudinella emarginula (St.enroos) : I, 2 T. parua (Ternetz) : 1, 2 7’. patina (Herman) : 2, 6 Trichocerca abilioi n. su. : 1 T. bicrisfata (Gosse) : i T. pagellata Hauer : 1 ** T. hollaerti De Smet : 2 T. longisefa (Schrank) : 2 T. porcellus (Gosse) : 2 T. pusilla (Jennings) : 1, 6 **

T. T. rotundata M?ers : 2 similis (Wierzejski) : 1, 2

The samples cont.ained some contract.ed monogo- nont rotifers of the genera Cephalodella, Euchlanis, Notommata and houles toget,her with many Bdelloi- dea. Al1 of these were deformed beyond identifica- tion.

In total, 66 rotifer species were identifled from the three samples available. Four of these were not pre- viously known, one of these, a Lecane, has been des- cribed elsewhere (Segers, 1994). Four ot,her species have not been recorded from the neotropical region before, one is new to Brazil. The most diverse genera were Lecane (39 %), followed by Trichocerca (13.6 %). This confirms exist.ing knowledge on the composit,ion of rotifer taxocoenosis in (sub)tropical littoral habi- tats (SEGERS et al., 1993 a). Most of the species recor- ded are common, cosmopolitic or pan(sub)tropical, probably warm-stenotherms and have already been recorded from the neotropical region (see KOSTE and JOSÉ DE PAGGI, 1982; KOSTE and BOTTGER, 1989: Lecane sola Hauer from Ecuador). Surprisingly, onr record of Lepadella quadricarinafa (Stenroos) IS the first from t,he Neotropics. This widely distributed species appears to be more common in temperate regions. Some of the species found are confined to the neotropical region; such are L. braziliensis Segers, L. eutarsa Harring and Myers and probably L. nelsoni Segers, toget.her with two of the species described below. D. sebastus and L. fuloa Harring and Myers are new world species which had not yet been recorded from the neotropical region.

Notes on the taxonomy and distribution of new or insufficiently known species are as follows.

178 H. SEGERS, S. S. S. SARMA

FAMILY TRICHOTRIIDAE

Mucrochaetus umericunus n. sp. (figs la-b)

TYPE LOCALITY

Permanent lagoon of Rio Branco, about 7 km S. of Boa Vist,a, Roraima, Brazil, 24 June 1987. C0nduct.ivit.y 5.7 pS ; 02 7.1 mg/1 ; TO (surface) 36.6 OC; pH 5.3. Leg. E. N. dos Sant.os-Silva.

MATERIAL EXAMINED

Female holotype (I.N.P.A. Rot-048), two female paratypes (one K.B.I.N. I.G. 27989 R.I. 13, one in R.IJ.G.).

DIFFERENTIAL DIAGNOSI~

The species cannot., by its single pair of dorsal spines, be confused wit.h any c.ongener. The species is strikingly similar to M. danneeli Koste and Shiel, known from Aust.ralia (KOSTE and SHIEL, 1983) and the Sout.h of India (F. K. KAKKASSERY, Ijers. Comm.) : bot.h have two pairs of short posterior spines and a similar round lorica. M. danneeli is reported to have only rudiments of dorsal spines (” anterosubmedian ” spines, see KOSTE and SHIEL, 1983; WULFERT, 1964). The postero-lateral and pos- tero-median spines are slightly slenderer and more elongate in M. danneeli than in M. americanus n. sp.

DESCRIPTION

Female : Contracted lorica almost circular, widest in post.erior t,hird, ent.irely covered (dorsally and ven-

la

1-l 50 c

Ree. Hydrobiol. trop. 26 (3) : 175-185 (1993).

trally) with small spinulets. Lateral margins of lorica smoothly rounded. Lateral, antero-vent,ral and antero-dorsal margins with rows of subequal spinu- lets, those on anterior margins smallest. Posterior margin with a pair of short, curved posterolateral and a pair of stout posteromedian spines. Posterome- dian edge convex, bearing two small spinulets. Ven- tral lorica flat, dorsal lorica with terraced median part, bearing two strong spines in anterior part. Lateral antennae in posterior region, on soc.le. Head when contracted tube-like with lateral folds, bearing the dorsal antenna and some relatively strong spinu- lets. Foot subterminally, partly covered, consisting of a rigid, elongate distal foot pseudosegment on a variably shaped, retractile basis. Two parallel-sided, equally long toes present. Posterior illoricate part of body (“ anal segment “) cont.ractile, bearing two pairs of spinulets, t.he median pair the longest.

Mule : unknown.

MEASUREMENTS

Lorica length (of cont,racted specimens, caudal spines not included) 80-86, width 77-91. Dorsal spine length 21-24, posterior spine length 3-4 (external pair) and 5-7 (interna1 pair). Foot pseudosegment length 20, toe length 18-20.

ETYMOLOGY

The specific name americanus is an adjective, referring to the species’ area.

DISTRIBUTION AND ZOOGEOGRAPHY

M. americanus n. sp. is SO far only known from its type locality.

The species may be a vicariant of the Oriental/ Australian M. danneeli.

Macrochaetus aspinus n. sp. (figs 2a-b)

TYPE LOCALITY

Permanent lagoon of Rio Branco, about 7 km S. of Boa Vista, Roraima, Brazil, 24 June 1987. Conductivity 5.7 PS; 02 7.1 mg/l; TO (surface) 36.6 OC; pH 5.3. Leg. E. N. dos Santos-Silva.

FIGS la-b. - Macrochaetzzs americanus n. sp, a : dorsal view, b : foot, ventral view.

Macroc.haetus americanus n. sp. a : eue dorsale, b : pied, rrue oentrale.

FIGS 2a-b. - Macrochaefus aspinas n. sp. a : dorsal view, h : foot, ventral view.

~Iacrochaetus aspinus n. sp. a : ane dorsale, b : pied, eue urnfrafe.

NEW OR LITTLE KNOWN ROTIFERA (~RA~IL) 179

MATERIAL EXAMINED

Female holotype (I.N.P.A. Rot-049), two female paratypes (one K.B.I.N. I.G. 27989 R.I. 14, one in R.U.G.).

DIFFERENTIAL DIAGNOSIS

Although its lorica is entirely covered by minute spinulets, M. aspinus lacks the large dorsal spines, characteristic of the genus. Only M. danneeli equally lacks such dorsal spines, but this species has a dif- ferent lorica shape and is armed with two pairs of caudal spines as in M. americanus n. sp. The t,otal absence of any large spine is unique to M. aspinus n. SP., which cari therefore not be confused with any congener. It is assigned to the genus Macrochaetus by its characteristic lorica shape being covered entirely by minut,e spinulets, by the shape of its head and foot when contracted, and by its trophi structure.

DESCRIPTION

Female : Contracted lorica slightly longer than wide, broadest medially, ent,irely covered (dorsally and ventrally) with small spinulets. Lat,eral margins of lorica smoothly rounded. Lateral, antero-ventral and antero-dorsal margins with rows of subequal spi- nulets, those on anterior margins smallest. Ventral lorica flat, dorsal lorica with terraced median part, with lateral ant.ennae in posterior region, on socle. Head when contracted tube-like with lateral folds, bearing the dorsal antenna and some relatively strong spinulets. Posterior end of lorica with a cen- tral, projecting dome and lateral, rounded parts. Subterminal foot partly covered, consisting of a rigid, elongate distal foot pseudosegment on a varia- bly shaped, retractile basis. Two tapering, equally long toes present. Posterior illoricate part of body contractile, covered with minute spinulets.

Male : unknown.

MEASUREMENTS

Lorica length (of contracted specimens) 76-82, width 72-76. Foot pseudosegment length 17, toe length 18-19.

ETYMOLOGY

The name M. aspinus (adj.) refers to the species’ unique characteristic, i.e. the absence of any large spine.

DISTRIBUTION

M. aspinus n. sp. has only been rec.orded from it.s type locality.

Rev. Hydrobiol. trop. 26 (3) : 17.5185 (1993).

FAMILY COLURELLIDAE

Lepadella costatoides Segers, 1992 ; new syuonym : L. latusinus striata Koste, 1992

Recently, both Segers (in : SEGERS et al., 1992) and KOSTE [in : KOSTE and BOTTGER, 1992 : Lepa- della latusinus striata (KOSTE, 1991), sic !] recognised and described a Lepadella having a dorsal lorica bea- ring three pairs of longit.udinal ridges and having a pair of acute postero-lateral projections on the foot aperture. The descriptions and figures by both authors clearly demonstrate that the same taxon is being dealt wit,h, and that both names are syno- nyms.

A subspecificity of the taxon with L. latusinus is doubtfull, as the taxon was found in co-occurrence with L. latusinus americana Myers (KOSTE and BOTTGER, 1992). Moreover, it has already been recognised as a c.osmotropical, warm-stenothermic species (SEGERS et al., 1992; 1994).

The description of Lepadella costatoides was publi- shed in October 1992, t.hat of L. latusinus striata in December 1992. As a consequence, the former name is the senior synonym and takes precedence over the latter.

FAMILY DICRANOPHORIDAE

Dicranophorus kostei Pourriot and Zoppi de Roa, 1981; new synonym : D. haZbachi Koste, 1981 (figs 3a-g)

In a sample from a temporary lagoon near Boa Vista, we found several large Dicranophorus match- ing the descriptions of D. kostei Pourriot and Zoppi de Roa and of D. halbachi Koste. The animais are characterised by having extraordinarily long, parallel-sided toes with short basa1 sheaths as in D. forcipatus (0. F. Müller), and by trophi as in figs 3a-c, having fused triangular or tooth-like pro- jections on the inner margins of the rami, and having epipharyngeal plat,es (fig. 3b) as accessorial trophi parts.

When comparing the ramus of specimens from dif- ferent origin, a striking variability is apparent. Remarkable differences are seen in size, shape of the tip and of the inner project.ions of the rami. These projections were found to be symmetric,al in the paratype of D. halbachi, slightly asymmetrical in our Brazilian material and slightly or strongly asym- metrical in animals from different populations in Nigeria.

KOSTE (1986) reports that the presence or absence of epipharyngeal plat.es is the single diagnostic cha- racter between D. kostei and D. halbachi Koste, des- cribed from Australia (KOSTE, 1981), but later also

1 XC) H. SEGERS, S. S. S. SARMA .

3b

t--------i 50 w

recmrtlrd from Paraguay (KOSTE, 1986). Such plates, howrvrr, may have passed unmentioned, as by most authors (e.g., HARRING and MYERS, 1928), although they are present. in most large dicranophorids. Exa- mination of some phot.ographs, kindly placed at. our disposition by Prof. R. Pourriot, revealed the pre- sence of such plat,es in D. kostei. Examinat,ion of t.he lrolot,ype and paratype incus of D. halbachi, deposi- ted in t.he Museum of the University of Kiel, Ger- many (Rot.. 76/77), and çomparison with other mate- rial, revealed a synonymy between D. kostei and D. halbachi. The record of Dicranophorus cf. halbachi from Nigeria (SEGERG et al., 1993 a) is hereby confir- med. D. kostei appears to have a pantropical distri- but ion.

As t.he description of D. kostei was published during the second quarter of 1981 and that. of D. hal- bachi during July 19S1, the former is t,he senior, valid name of t.hr taxon.

FAM JI,Y TRICHOCERCIDAE

Trichocerca abilioi n. sp. (figs 4se)

TYPE L~CALITY

Temporary lagoon along rio Brama, about 5 km S. of Boa Vista, Roraima, Brasil, 24 ,June 1987. C0nduct.ivit.y 5.7 PS; 02 7.2 mg/l; TO (surface) 32.9 OC; pH 6.1. Leg. N. dos Santas Silva.

MATERIAL EXAMINED

Female holotype (I.N.P.A. Rot-047), three female parat.ypes (one K.B.I.N. I.G. 27989 R.I. 15, two in

FI~;S Sa-g. - Dicranophorus kosfei, t,rophi. a : t,rophi (ventral view) ; b : epipharyngeal plat.es ; c : fulcrum (lateral view); d-g : right. ramus. d : parat.ype of D. halbachi; e, f : Nigerian specimens; g : Brazilian

specimen. Dicranophorus kost,ei, frophi. a : frophi (eue rren- fraie) : b : plaques épipharyngéoles; c : fulcrum (rrue latérale) ; d-g : ramus droif. d : parafgpe rie D. halba- chi; e, f : spt!cimens nigériens; g : spécimen brésilien.

R.U.G.), one trophi preparation (R.U.G.). Several specimens seen in samples from the Pant.anal region, Brazil (August 1955, leg. A. L. Oliveira-Neto), one specimen from lake Iyi-Efi, Nigeria (February 1991, see SEGERS ef al., 1993 a)

DIFFERENTIAL DIAGNOSJS

Trichocerca abilioi n. sp. belongs to a group of elongate Trichocerca wit.h subequal tocs, SUC~ as T. tiyris (0. F. Müller), T. myersi (Hauer), T. scipio (Gosse), T. uaryai Wulfert. or T. kostei Segers. The disposition of the projections of the head aperture, wit.h its conspiçuous triangular ventral projection, and t,he shape of its trophi easily distinguish t.he spe- cies. The external morphology of the Nigerian speci- mens is ident,ical to that of the Brazilian mat,erial, their trophi have more acutely point#ed rami but are otherwise highly similar.

DESCRIPTION

Female : Lorica (figs 4a, b) relat,ively stiff. Body elongate, slightly curved. Margins of head aperture ventrally with a broad-based, triangular projection, left-lateral side with a shallow median projection anterior of a short. striped field, right lateral side with inconspicuous t,rapezoidal striped field ven- trally. A shallow subdorsal keel on left side of body in anterior third, an elongate striped field subdor- sally on right. side, reaching up t.o medially. Foot. short, terminal. Toes subdistally, held ventrally. Toes spiniform, curved proximally and distally, the right one about half as long as the left one. Each of these with two subst,yli of different, shape and length near their basis. Openings of lat,eral antennae in dis-

I&V. Hydrobiol. trop. 26 (,3) : 175-185 (1993).

ïvEw 0~ LITTLE KWOWN ROT~~ERA (BRAZIL) 181

4d

>

FIGS 4a-e. - Trichocerca abilioi n. sp. a, h : lateral views; c-e : trophi. c : ventral, d : lateral, e : dorsal view.

Trichocerca abilioi n. sp. a, b : vues IatéraZes; c-e : trophi. e : me oentrale, d : latérale, e : dorsale.

ta1 part of body, the left more distally than the right,. Eye present..

Trophi (figs 4c-e) asymmetrical. Fulcrum elongat.e, with median antero-ventral crest and t,erminal basa1 plate. Left ramus with large, outwards directed alu- lus. Suprauncus wit,h rows of long, inwards-curved teeth anteriorly on the ventral side, and a antero- la.teral spine. Supraramus present. Left uncus with single basa1 part, and fan-shaped distal part consis- ting of 3-4 fused teeth. Left manubrium elongate, widened proximally, distally with simple cruch. Right ramus smaller than left, with straight alulus.

Suprauncus with antero-median row of short, fused teeth and rounded antero-lateral projection. Supra- ramus present. Right uncus and manubrium st.rong- ly reduced.

M&e : unknown.

MEASUREMENTS

Body 1engt.h 162-209 (198), height 39-54 (49), foot 1. 10-16 (16), trophus 1. 55-60 (57), right t,oe 1. 26-44 (42), left t,oe 1. 44-62 (broken) (measurement.s on Nigerian spec.imen bet.wrrn brackets).

Fulcrum 1. 43-45, left manubrium 1. 40, left, ramus 1. (incl. alulus) 22-26, right ramus 1. (incl. alulus) 20-22.

ETYILIOLOGY

The species is named after Abilio Lopez de Oli- veiro-Neto, who originally collectrd and rccognised the species as new.

T. nbi2ioi II. sp. occurs in South America (Brazil : type locality and several places in the Pantanal region), and in Africa (Nigeria).

Trichocerca hollaerti De Smet, 1990 (figs 5x-k)

COMMENT~

Trichocerca hollaerfi is an easily recognisable spe- cies which, according to DE SBIET (1990), cari be c,onfused only with T. fZageZlatu Hauer (figs 6a-d). Both species have a similar head aperture, disposi- tion of the toes and substyli and a generally similar trophi structure. They cari hardly be mistaken, considering that T. f2agellnfa has a shallow and short. dorsal keel, a rounder lorica and a relatively long, smoothly curved left t.oe.

Howevar, as T. hollaerfi is c,haracterised by having a lateral keel over thfi entire body, by a head aper- t.ure having longitudinal folds and by having a single elongate right, and a S-shaped, short left t.oe, it, resembles most T. lnphoessa (Gosse). They differ only by the struct,ure of t-heir t,rophi, that, of T. lophoessa has SO far only heerl figured by STETNBERGER (19%). Especially its bifid left alulus and single-sided distal cruch of its left. manubrium dist inguishes T. lophoessa from T. holluerfi.

T. hollaerfi has, aftrr its description from Zaire, been recorded from Nigeria (SEGERS ef al., 1992). The record of T. lophoessa from Madagascar (figs 5c, f-h ; SEGERS, 1992) conctxrns a misidentified T. hollaerfi. The present, record ie the first outside Africa.

R~U. Hydrobiol. frop. 26 (.3) : 175-185 (I$$d).

182 II. SEGERS, S. S. S. SARMA

1-j 50 pm (5a-c) 1-l 25 pm (Sd-h)

FIGS 5a-h. - Trichocerca hollnerti De Smet. a : late- rai view ; b : foot and toes, ventral view ; c : sub- vent.ral view ; d-h : trophi. d, f : ventral view, e, g : dorsal view, h : lateral view (c, f-h : Madagascan

specimen). Trichocerca hol1aert.i De Smef. a : vue latérale; b : pied et orteils, vue venfrale; c : vue subvenfrale; d-h : frophi. d, f : vue ventrale, e, g : vue dorsale, h : vue

laférnle (c, f-h : spécimen malgache).

Trichocerca rotundata Myers, 1937 ; new synonym : T. parvula Carlin, 1939 (Figs 7a-d)

COMMENTS

A single specimen of this rare species was found in localitg 2 (see above). The spec.ies cari be confused with T. porcellus (Gosse) and T. musculus Hauer (see KOSTE, 1978 ; e.g., Diurella porcellus after JENNINGS,

1903 ?), but is distinguished by its smaller size and differently shaped trophi with simple left alulus (bifid in T. musculus and T. porcellus) and slightly differentiated terminal part of left manubrium (wit,h strong distal crutch in T. musculus and T. porcellus).

Trichocerca rotundata appears to have been over- looked by most, authors dealing wit.h the Palaearctic, fauna. The species has, after its description, only

Heu. Hydrobiol. frop. 26 (3) : 1%18~5 (1993).

NEW OR LITTLE KN0wN R~TIFERA (BRAzIL) 183

FIGS Ga-d. - Trichocerca flagellafa Hauer. a : ven- tro-lateral view ; b-c : trophi. b : ventral, c : dorsal

view ; d : left uncus. Trichocerca flagellata Hauer. a : vue venfro-latérale; b-c : frophi. b : vue ventrale, e : vue dorsale; d : uncus

gauche.

FIGS 7a-d. - Trichocerca rofundafa Myers. a : left lateral view, b : foot and toes, right lat,eral view,

c-d : trophi. c : ventral, d : dorsal view. Trichocerca rotundata Myers. a : vue laférale gauche, b : pied et orfeil, vue laférale droite, c-d : frophi. c : vue

venfrale, d : vue dorsale.

6d

?a

been treated by NOGRADY (1979), who found the spe- cies in Canada. Similar specimens have been recor- ded and described from Europe under the name Tri- chocerca parvula Carlin. The synonymy of the two follows from a comparison of the external morpho- logy and trophi structure of T. parvula as reported by KOSTE (1978) and WULFERT (1940) wit,h the report of T. rotundata by MYERS (1937) and NOGRADY (1979), and of the present material.

CONCLUSION

Our results demonstrate that the taxonomy of Brazilian Rotifera remains incompletely known, even though t.he region is the most intensively stu- died tropical count,ry. As a11 species treated are litto-

1-1 50 pm (6a, 7a-b) 1-j 25 pm (6b-d, 7c-d)

ral, it appears, as,usual, to be the littoral rotifera in particular that are insufficient,ly known (SEGERS et al., 1991 ; 1992).

More and more evidenc.e becomes available t.hat illustrates a relation between the rotifer faunas of the tropical region of South America and Afric.a. In previous papers (SEGERS, 1994; SEGERS et al., 1993b), some taxa that either are known from both regions only (e.g., Lecane dumonti Segers), or, at least, have close relatives in both regions (e.g., L. nelsoni) were ident.ified. An additional example is described here (T. abilioi). These, together with a further list of species, rec.orded from Africa and South America (Keratella americana Carlin, Lecane climacois Harring and Myers, L. decipiens [Murray], L. myersi Segers and Lepadella minoruoides Koste and ROBERTSON : SEE SEGERS et al., 1993a),indicate that the hypothesis of recent faunal exchange, for-

Rev. Hydrobiol. trop. 26 (3) : 175-185 (1993).

181 H. SEGERS, S. S. S. SARMIA

WCIF~~ hy SEGEHS et al. (1993 a) is prohably not t.he 0111~ fact-or playing a role. It may be truc for an easlly recognizable, common American species as K. clmericana, tbat- has been found only once or t-wice in thr old world, but cari hardly ac.count, for c.ases of spfacies as rare as L. dumonii, L. climacois, L. myersi, L. nelsoni, Lepadella minoruoides and T. abilioi. -44t. least in some cases should the disjunct dist-ribution of these species be treated as demonstra- ting an ext.ant zoogeographical relation hetween the t.wo ragions.

The second author acknowledges a grant. from t.he Belgian Administration for Development & Cooperation, to attend the “ Int.ernat.ional Training Course on Lake Management. : the Zooplankton “, and Prof. 1.1. .J. Dumont. who enabled his pro- longed st.ay at. t.he 1nstit.ut.e of Animal Ecology, University of Ghent, Belgium. We thank Prof. R. Pourriot for kindly provi- ding photographs of the t.ype of D. Izostei, and for his comments on the synonymy of D. kostei and D. halbachi.

Manzzscrif accepté par le Comifë de rédaction le Ier novembre 1993

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